The legacy of Nazi war crimes resurfaced on Monday when a German magazine reported that a trove of artworks looted from Jewish collectors had been discovered in a Munich apartment. According to the weekly Focus magazine, the hoard of paintings could be worth more than a billion dollars, as it includes masterpieces by Henri Matisse, Pablo Picasso, Marc Chagall and Paul Klee. German authorities discovered the works almost by accident in the home of Cornelius Gurlitt, the son of a Munich art collector. As the details of the case have continued to emerge, so have the questions about the German authorities’ decisionmaking. Here are some of the more pressing questions raised so far:

Why are we only learning about this now?
According to Focus, the roughly 1,500 paintings in Gurlitt’s collection were found in the spring of 2011, when authorities searched his home in relation to charges of tax evasion. Tax officials and police thus seem to have known about the artworks for nearly three years, but they failed to make their discovery public. This has already raised concerns about a possible cover-up, with Focus alleging that the authorities “kept the secret” for years.

How did Gurlitt sell the paintings without arousing suspicion?
The 80-year-old recluse reportedly made his living by selling the paintings at auction from time to time. Even after the 2011 raid on his apartment, he managed to sell off another one of his paintings — a work by German Expressionist painter Max Beckmann — for roughly a million dollars at the Lempertz auction house in Cologne, according to the Focus report.

How could the son of an alleged Nazi collaborator stay off the grid?
Gurlitt’s father Hildebrandt was known in international art circles for helping Nazi leaders monetize the artworks seized from Jewish families. Hildebrandt Gurlitt, an historian and art dealer who was Jewish on his mother’s side, had reportedly fulfilled this role at the request of Adolf Hitler’s Minister of Propaganda, Joseph Goebbels. But the art dealer’s only surviving son managed to avoid registering with German tax authorities and social-services organizations for years. “He was a man who didn’t exist,” a German official was quoted by Focus as saying.

Why did investigators believe that the works had been destroyed?
At the end of World War II, Hildebrandt Gurlitt was reportedly captured by American forces and claimed during interrogation that his family’s art collection had perished during the 1945 bombing of Dresden, where the family had a home. Because of his Jewish heritage, the elder Gurlitt was deemed a victim of Nazi persecution and released. He continued trading art until his death in a car accident in 1956. It is not clear whether the postwar government in Germany ever tried to confirm whether Gurlitt’s art collection had really been destroyed.

How seriously does Germany take warrants for stolen art?
According to Focus, 200 of the works found in the younger Gurlitt’s apartment are the subject of international warrants. One of the works by Matisse reportedly belonged to the Jewish collector Paul Rosenberg, who was forced to leave his collection behind in Paris after fleeing the Nazi invasion of France in 1940. His granddaughter, Anne Sinclair, a prominent French-American journalist who was married to former IMF chief Dominique Strauss-Kahn, has been campaigning for decades to get her family’s art collection back.

How did Gurlitt manage to hide his wealth?
In 2010, German customs officials conducted a routine inspection of Gurlitt’s baggage on a train returning from Switzerland, Focus reported. The €9,000 in cash they found in his possession raised the suspicion of German tax authorities, who then secured a warrant to search Gurlitt’s cluttered apartment the following year. His apparent visits to Switzerland, the world’s largest tax haven, will likely raise questions about his use of offshore banks to stash the money he earned from selling paintings. Under the secrecy laws that govern Swiss banks, Gurlitt would have been able to hide his ownership of Swiss bank accounts or safe-deposit boxes from German authorities.